The present invention relates to a magnetic head for use in an information recording apparatus utilizing a magnetic recording medium, and more particularly to a magnetic head having a narrow track width for performing magnetic recording on a magnetic medium at a high recording density.
In order to attain high density recording and large capacity recording in magnetic recording, it is necessary to make the track width defined by a magnetic head narrow. Further, the coercivity of a recording medium has been increased in accordance with the high density recording and the large capacity recording. Thus, the magnetic head is required to define a narrow track width and moreover to generate a strong magnetic field capable of magnetizing the magnetic recording medium.
As a method of reducing the track width defined by a magnetic head, processes such as sputtering and ion-milling are used for making small the dimensions of the magnetic head corresponding to the track width. According to this method, however, a magnetic path at the tip of a magnetic pole has a narrow cross section, and thus the magnetization of the magnetic pole is first saturated at the tip. Accordingly, the magnetic pole cannot generate a strong magnetic field capable of magnetizing the recording medium. In order to solve this problem, the thickness of the magnetic pole in a longitudinal recording direction is increased, and thus the magnetic saturation at the tip of the magnetic pole can be suppressed.
In order to make a magnetic head correspond to a desired track width in manufacturing processes, ion-beam etching using a carbon fluoride gas is carried out for, for example, for an aluminum oxide (Al.sub.2 O.sub.3) film. That is, dimensions of the magnetic head corresponding to the track width are determined by the alumina masking method (refer to JP-A-60-37130). Further, in order to obtain a magnetic head which has a thick magnetic pole, that can define the width of a recording track accurately, and that generates a strong magnetic field capable of magnetizing a high-coercivity recording medium, a method of manufacturing a magnetic head has been proposed in which an upper pole is divided into two parts (refer to, for example, JP-A-63-81209).
Further, a method of making the small dimensions of a magnetic head corresponding to a track width, by stepping the tip of a magnetic pole after the air bearing surface of the magnetic head has been polished, is described in, for example, an article by J. Kishigami et. al. (IEEE Trans. Magn., Vol. 24, No. 6, pp. 2841-2843, Nov. 1988). In this article, the tip of the magnetic pole is stepped by the ion-milling method using a photoresist layer as a masking film.